The invention pertains to an adjustable torque wrench which is capable of being preset to specific torque values and which includes a means for indicating when the specified torque is reached.
Torque wrenches which can be set to desired torque values are known in the art. Such torque wrenches substantially reduce the time and effort for setting a specific torque when tightening bolts, nuts, spark plugs, etc. In one known type of prior art arrangement, an externally threaded shaft is received within an internally threaded tube for the purpose of setting the torque value. Over time, wear and tear will occur on the threads between the shaft and tube which results in a reduction in the accuracy of the torque setting system.
It is also known in the art of torque wrenches to have a torque release connection between a manually engageable handle and a torque applying member. In these types of wrenches, as represented by U.S. Pat. Nos. 2,996,940 and 3,355,970, the torque setting value of the wrench can be adjusted by varying the mechanical advantage of the level-type connection between the wrench handle and the torque applying member. When a preset torque value has been reached, the releasable connection between the member and the handle prevents further torque application through the torque-applying member. The release of this connection provides an abrupt indication that the desired, preset torque limit has been reached.
Therefore, based on the above discussed prior art, there exists a need for a torque wrench having an adjustable torque setting which does not need to be recalibrated or will lose its accuracy over a long period of time. There also exists a need for an adjustable torque wrench which can provide a readily determinable, non-abrupt indication when the preset torque value has been reached.
It is therefore the object of the present invention to provide an adjustable torque wrench having a readily and accurately adjustable torque value setting mechanism in the form of a spring biased slide assembly and a means for indicating, preferably audible, when the preset torque value has been reached.